1. Field of the Invention
This invention relates to a stable aqueous suspension of particulate matter selected from the group consisting of ash, slag, and char, and mixtures thereof, which are produced in a partial oxidation process. More particularly, it pertains to a novel pumpable stabilized aqueous suspension comprising an alkyl-substituted amine-based surfactant and particulate matter selected from the group consisting of ash, slag, and char, and mixtures thereof, that are produced by quench cooling or scrubbing a raw effluent gas stream from a process for the partial oxidation of solid carbonaceous fuel.
2. Information Disclosure Statement
Solid carbonaceous fuels such as coal, petroleum coke, shale, asphalt, etc. have been dispersed in liquid mediums such as water and liquid hydrocarbons to form pumpable slurries. These slurries have been introduced as feedstock into partial oxidation gas generators in processes disclosed for example in coassigned U.S. Pat. Nos. 3,544,291; 3,620,698; 4,104,035; 4,265,407; and 4,328,008.
It is well known to those skilled in the art that the partial oxidation of solid carbonaceous fuels such as coal, petroleum coke, hale, asphalt, etc. produces synthesis gas comprising primarily H.sub.2 and CO as well as particulate ash which primarily comprises inorganic slag and carbonaceous char material. This particulate material may be discharged from the partial oxidation process for eventual disposal or recycled in part or in whole to the partial oxidation reactor as a charge fuel either alone or in admixture with other solid carbonaceous charge fuel material, in order to: (1) achieve the partial oxidation of the remaining carbonaceous material (i.e. char); and (2) utilize the inorganic compounds contained within the slag as a fluxing agent to improve solids removal from the partial oxidation reactor. It would therefore be advantageous to have a stable aqueous suspension of a slag and char mixture for pumping, either for disposal of the material or for partial or total recycle of the slag and char to the partial oxidation reactor. Stable liquid suspensions comprising carbonaceous material are disclosed, for example, by the following:
Coassigned (Najjar et al.) U.S. patent application Ser. No. 674,898, filed Nov. 26, 1984 discloses a stable aqueous suspension of slag, fly-ash and char which comprises 1.0-50.0 wt. % of particulate matter selected from the group consisting of slag, fly-ash, char and mixtures thereof and 0.1-10.0 wt. % of a surfactant which is an anionic or nonionic adduct of an alkyl phenol and polyoxyalkylene or polyoxy propylene;
(Koskan et al.) U.S. Pat. No. 4,530,701 discloses a process of manufacturing a coal-fuel composition which comprises coal macro particles in a petroleum liquid fuel, water, an alkaline fluxing mineral material, and a coal anti-sedimentation surfactant which is a fatty acid alkenol amide;
(Mark) U.S. Pat. No. 4,478,603 discloses a stabilized high solids content coal-aqueous mixture comprising water, coal, a polyalkylene oxide nonionic surfactant and a polyelectrolyte surfactant;
(Meyer) U.S. Pat. No. 4,475,924 discloses a liquid-solid fuel composition comprising beneficiated coal char derived from the pyrolytic destructive thermal distillation of coal in the absence of oxygen, and a C.sub.1 -C.sub.4 alcohol.
Co-assigned (Wiese et al.) U.S. Pat. No. 4,304,572 discloses a pumpable coal-water slurry comprising coal present in a concentration of at least 50% by weight, NH.sub.4 OH present in an amount between 0.1-5.0 wt. %, and an anionic surfactant comprising a salt of an organic sulfonic acid present in an amount between 0.01-3.0 wt. %;
(Grosse et al.) U.S. Pat. No. 4,392,865 discloses a stabilized hydrocarbon-water fuel comprising coal, oil, a relatively low molecular weight hydrophilic-lipophilic agent, and a high molecular weight swellable material, having a molecular weight of at least 500,000;
(Solbakken) U.S. Pat. No. 4,145,189 discloses a clean burning, low sulfur liquid fuel suspension which comprises coal char and liquid oil derived from a pyrolysis process, water, and an optional stabilizing agent;
Co-assigned (Cole et al.) U.S. Pat. No. 4,104,035 discloses a solid fuel-water slurry suitable for use as feed to a partial oxidation reactor which comprises hydrothermally treated subbituminous coal and lignite, water, and a surfactant which is a salt of an organic sulfonic acid; and
(Thomas) U.S. Pat. No. 4,094,810 discloses a process for producing an aqueous slurry of an ash concentrate composition comprising insoluble coal products, the process comprising mixing water, insoluble coal products derived from a coal deashing process, and an anionic or nonionic surfactant.
It is the object of this invention to provide a pumpable aqueous suspension of slag and char derived from a partial oxidation process, the suspension having reduced viscosity and increased resistance to sedimentation.
It is one feature of this invention that such a pumpable aqueous suspension facilitates disposal of slag and char material or the recycling of such material to the partial oxidation reactor.
The instant invention is advantageous in that suspensions of the instant invention show improved stability and resistance to settling over aqueous suspensions of partial oxidation process slag and char which do not contain the abovedescribed surfactant material.